To be fair I had alt-tabbed to go check a run through of the level on YouTube just to get an idea of how people approached it, but I've alt-tabbed in SMB before without issue, so it was frustrating nonetheless.

I felt like the last level was the hardest, too. The first was actually VERY fun, it felt like a challenge. The second level was pretty easy, not really challenging but more of a test of patience. The last level just felt like a battle against the Kid's slow mechanics.

I feel like the third one, while it was arguably the hardest and required the most focus and perfect timing, was still tolerable. I didn't like the second one at all, it was more annoying since it took a lot more time simply due to the fact that most of the deaths happened after about 10-20 seconds into the level (the third elevator for me mainly).

Luckily, patience pays off and I unlocked The Kid eventually even after having to complete the first two levels for the second time.

To be fair I had alt-tabbed to go check a run through of the level on YouTube just to get an idea of how people approached it, but I've alt-tabbed in SMB before without issue, so it was frustrating nonetheless.